A perplexing problem?

[Anonymous]

I'm trying to build a multi faceted hollow model of an elephant. It stands 900mm high. Now if I wanted to construct it out of thin cardboard, I could open the .stl in Pepakura and get a flat 2d drawing with glue tabs added. That's fine for paper but I want to construct it from mdf, let's say 3mm thick. Now I've got a thickness to the faces, the edges will be glued to assemble the model. These edges have multiple mitre angles relative to the angle of the adjacent facet.

I'm looking for a methodology whereby I can generate a body to send to a cnc that cuts out the plan view and mitres the edges to the required angles (sometimes on the reverse side), so a 5th axis cnc is required. If I was to manually draw a plane through every face intersection, I could manually draw up each body, but I'm hoping there's an easier solution? In the pics, the first is a 3d body of an elephants foot. The close up shows a junction of 3mm thick faces that won't fit neatly together unless the edges are mitred to half the included angle. Every mitred edge angle will be unique. Any suggestions appreciated.

[prainsberry]

You had me at perplexing... 🙂

So I'll tell you there is not a super quick way to do this out of the box, but it is something you could definitely accomplish with a script.  Any background in writing code?  You can use the FUsion 360 API with Python.

Basically what you would need to do is:

• Get all faces on model
  • Calculate the half angle at every edge of every face to its adjoining face
  • Build construction plane (maybe)
• Extrude each face as new body
• Compare each side face to its corresponding construction plane
  
  • Use either cut, draft, extrude or something to modify the side face to match proper angle (this will be tricky)
• Could get fancy and then lay each part out flat

Now all that being said this is no small task. As a person who has gone from zero to API over the past year or so i can tell yu it is possible but depends on how much time you are willing to put into learning the code side depending on your background.

[promm]

Hello @Anonymous,

We do not have a tool that automatically miters edges based off of faces.  If I may, I would suggest spitting up the model in a different way.  I would slice the model up in layers that you would stack using 123D Make.  I would put some holes for dowels that you could use to align them as you stack.  Please watch this video that was done for a class at AU.  We made the mannequin using the same workflow I am suggesting.

http://www.autodesk.com/products/fusion-360/blog/textile-fabric-design-class-coming-au-2016/

Let me know if you have any questions,

Mike Prom

[Anonymous]

Thankyou Patrick, for your reply. No, I'm not into Python.  Thinking outside the box though, I've come up with another idea? F360 has an issue with "Thicken" for complex triangulated bodies.....it just can't convert them to say 3mm thick wall! Maybe it's my computer hardware? If I was to use "Scale" to achieve a body 3mm smaller than the original, I could now print out a flat pattern for the outside and inside faces. If I then overlayed them, I could measure the width of the parallel edge difference "X" and knowing that "Y" is a constant say 3mm, that would give me "Z" the sloping bevel, and therefore the angles.

Again a big job manually, but it'd be a start and use simple math. One thing is for sure though, I've stumbled across something that no one is doing much of? That is building multi faceted bodies with a material of a reasonable thickness and then getting a CNC to cut it out. That smacks of a "niche", and we all know the old adage, "Find a niche, get good at it, and you will prosper?"....lol

All the best,

Paul

[Anonymous]

Interesting video promm, and thanks for the referral. Not quite the solution I was after, but appreciate your input.

Cheers,

Paul